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Biomedical subjects

D A Chad

Publications and source records attributed to D A Chad.

At least 19 recordsLinked to original sources
PubMed1998

Neuromuscular disorders and acute respiratory failure.

This article discusses the assessment and management of rapidly progressive weakness due to neuromuscular disorders. The authors review elements helpful in determining the causes of weakness including pertinent history and laboratory studies. Disorders are classified according to the level of the motor unit involved and triage/management decisions are described. In addition, respiratory function assessment is reviewed. The latter part of this article is devoted to evaluation and management of two of the most common disorders, Guillain-Barré syndrome and myasthenia gravis.

Diagnosis, Differential↗
PubMed1996

Severe cranial nerve involvement in longstanding demyelinating polyneuropathy: a clinicopathologic correlation.

Onion bulb formations involving cranial nerves are an unusual pathologic feature. We report the postmortem neuropathologic findings in a 69-year-old man with a longstanding neuropathy characterized by progressive muscle weakness, sensory ataxia and multiple cranial nerve abnormalities. Electrodiagnostic testing disclosed features of an acquired demyelinating polyneuropathy. Treatment with corticosteroids and plasmapheresis resulted in no change in his neurologic status, and the patient died after repeated episodes of pneumonia and sepsis. Autopsy showed widespread onion bulb formation in cranial nerves III, IV, V, VI, X, XI and XII, anterior and posterior spinal nerve roots, dorsal root ganglia and multiple peripheral nerves, some of which also had foci of epineurial perivascular inflammation. Muscle sections revealed severe neurogenic atrophy. This case demonstrates that, in longstanding acquired demyelinating neuropathy, the cranial nerves also undergo repetitive cycles of demyelination and remyelination resulting in severe weakness of the bulbar musculature and histologic features of hypertrophic neuropathy.

Aged↗
PubMed1996

Cognitive dysfunction as the major presenting feature of Becker's muscular dystrophy.

We report four patients, currently aged 15, 17, 19, and 42 years, with X-linked dystrophinopathy who presented with mental retardation (IQ range, 60-68) and psychiatric disturbance in the absence of muscle weakness. All patients had elevated serum creatine kinase and dystrophic changes on muscle biopsy. There were alterations in the size and abundance of dystrophin on immunohistochemistry and immunoblotting in all cases, consistent with a molecular diagnosis of Becker's muscular dystrophy. Two patients had deletions of the dystrophin gene on DNA analysis. These findings suggest that Becker's muscular dystrophy may be associated with a predominantly neuropsychiatric presentation and that dystrophinopathy should be considered in the differential diagnosis of unexplained cognitive or psychiatric disturbance in males. Serum creatine kinase may provide an adequate screening test in this clinical situation.

Adolescent↗
PubMed1994

Cardiomyopathy of limb-girdle muscular dystrophy.

OBJECTIVES: This study sought to find an association between dilated cardiomyopathy and limb-girdle muscular dystrophy. BACKGROUND: Cardiomyopathy has been seen in various neuromuscular disorders, but it has not been recognized to be associated with limb-girdle muscular dystrophy. METHODS: We investigated three sisters with well documented limb-girdle dystrophy and congestive heart failure by the 3rd decade of life. All underwent noninvasive evaluation of left ventricular systolic function by both echocardiography and radionuclide scanning, and one also had cardiac catheterization. Deoxyribonucleic acid (DNA) linkage analysis was performed in these affected subjects and in the unaffected family members, and DNA was extracted from mononuclear cells with primer sequences for three chromosome 13q microsatellite markers. RESULTS: The parents had no evidence of clinical disease, but all three sisters had echocardiographic evidence of dilated cardiomyopathy. The sister with additional evidence of left ventricular dysfunction of cardiac catheterization had no coronary artery disease. The affected subjects had the same paternal allele for three potential markers of limb-girdle muscular dystrophy but different maternal alleles. The very small family size did not permit statistical confirmation or refutation of linkage for chromosome 13q markers. CONCLUSIONS: Demonstrable cardiomyopathy accompanying limb-girdle muscular dystrophy and its probable genetic associations require continued investigation by anticipating the cardiomyopathy in limb-girdle muscular dystrophy.

Adult↗
PubMed1993

Acute myopathy and neuropathy in status asthmaticus: case report and literature review.

A 38-year-old woman developed acute, severe weakness during the treatment of status asthmaticus that included high-dose intravenous corticosteroids. A muscle biopsy and EMG indicated a myopathy, and nerve conduction studies disclosed a neuropathic component. In association with corticosteroid tapering, the clinical, EMG, and nerve conduction abnormalities resolved. In some patients, intensive treatment of status asthmaticus may cause a reversible, toxic disorder of muscle and nerve.

Acute Disease↗
PubMed1993

Myopathy in the elderly: evaluation of the histopathologic spectrum and the accuracy of clinical diagnosis.

We undertook a retrospective clinicopathologic study to ascertain the spectrum of histopathologic muscle biopsy changes in the elderly thought to have a myopathy, and to determine the accuracy of clinical diagnosis of myopathy in the elderly compared with a younger control population. We compared muscle histology and case histories, as well as EMG and creatine kinase (CK) data, obtained over 10 years from 77 consecutive patients aged 65 years or older (75 +/- 6, mean +/- SD; group 1) with those from 104 patients aged 30 to 50 years (group 2). Prominent myopathic features were present in 42% (group 1) versus 51% (group 2) of all biopsies. Neurogenic changes (17% versus 9%, p < 0.04) and type II fiber atrophy (22% versus 6%, p < 0.0005) were more common in the elderly, whereas normal findings tended to be less frequent (19% versus 35%). In at least 68% of patients in both groups with the histologic diagnosis of myopathy, either the CK was elevated or the EMG was consistent with that diagnosis. Our study indicates that (1) the spectrum of histopathologic changes in the two groups differs because of a higher frequency of neurogenic change and type II atrophy in the elderly, and (2) the accuracy of clinical diagnosis of myopathy in the elderly approximates that in a younger population.

Aged↗
PubMed1991

Coexistence of Lambert-Eaton myasthenic syndrome and subacute cerebellar degeneration: differential effects of treatment.

A 61-year-old woman presented with two paraneoplastic neurologic disorders--Lambert-Eaton myasthenic syndrome (LEMS) and subacute cerebellar degeneration (SCD)--that antedated the diagnosis of small-cell carcinoma of the lung by 15 months. Plasmapheresis initiated before the identification of the tumor had a beneficial effect on LEMS but did not affect the SCD. Chemotherapy administered for treatment of the primary tumor was also associated with improvement of LEMS but, like plasmapheresis, had no effect on SCD. While the pathogenesis of both LEMS and SCD is thought to be mediated predominantly by humoral immune factors, a differential therapeutic response indicates that mechanisms of tissue damage or susceptibility to tissue injury, or both, differ in these two disorders.

Female↗
PubMed1991

Neuromuscular complications of systemic cancer.

In patients with cancer, neuromuscular dysfunction often develops as a result of some combination of direct effects of the cancer, from complications of therapy, or from paraneoplastic syndromes. Direct effects include leptomeningeal involvement by tumors (most frequently of the breast and lung) causing polyradiculopathy and compressive brachial and lumbar plexopathies that produce distinctive and typically painful syndromes. The differentiation between radiation and tumor-associated brachial plexopathies may be difficult, however. Peripheral neuropathy is an important dose-limiting toxic side effect of two commonly utilized agents, vincristine and cisplatin. Recent studies have suggested that this complication may be ameliorated or even prevented by prophylactic administration of protective agents. Finally, cancer can cause neuromuscular dysfunction through more remote effects and can produce a variety of paraneoplastic syndromes that include subacute sensory neuropathy. Lambert-Eaton myasthenic syndrome, and the neuropathy associated with paraproteinemia. In some syndromes, the presence of specific antibodies that cross-react with both neuromuscular tissues and primary tumors strongly suggests an immune-mediated pathogenesis. In some patients, immunosuppressive therapies and plasmapheresis may relieve symptoms.

Humans↗
PubMed1990

Human immunodeficiency virus (HIV)-associated myopathy: immunocytochemical identification of an HIV antigen (gp 41) in muscle macrophages.

In a patient with acquired immunodeficiency disease syndrome (AIDS) and muscle weakness, a muscle biopsy specimen disclosed degeneration of muscle fibers, regeneration, and focal endomysial mononuclear inflammation. A conspicuous feature was the presence of perivascular macrophages within the endomysium that showed positive immunostaining for human immunodeficiency virus (HIV) (gp 41) antigen. HIV was not detected within myofibers. Our findings suggest an important role for the HIV-infected macrophage in the pathogenesis of this myopathy.

Acquired Immunodeficiency Syndrome↗
PubMed1989

AAEE case report #20: hereditary motor and sensory neuropathy, type I.

A case study is reported regarding a 32-year-old man with classic clinical and electrophysiologic features of hereditary motor and sensory neuropathy, type I (HMSN I), a slowly progressive autosomal dominant condition marked by slow motor and sensory velocities and generalized segmental demyelination. Another clinically similar autosomal dominant neuropathy (HMSN II) is distinguished from HMSN I by nearly normal nerve conduction velocity. Acquired demyelinating neuropathy may occasionally resemble HMSN I clinically, but the former demonstrates electrophysiologic features not seen in the latter such as conduction block, dispersed compound muscle action potentials, and differential slowing of conduction velocity. Neuropathologic studies of HMSN I suggest that both neuronal and Schwann cell distrubances play a role in pathogenesis.

Adult↗
PubMed1989

Chronic cough as the presenting symptom of oculopharyngeal muscular dystrophy.

A patient had chronic, persistent cough as the presenting symptom of the neuromuscular disorder oculopharyngeal dystrophy (OPD). The presence of a significant smoking history initially resulted in the cough incorrectly being attributed to COPD. By using a systematic diagnostic approach, the correct etiology was determined.

Aged↗
PubMed1988

Amyotrophic lateral sclerosis. Recent advances in pathogenesis and therapeutic trials.

We reviewed the current status of pathogenesis and therapeutic trials in amyotrophic lateral sclerosis (ALS). Clinical studies have identified several rare but definable causes for apparent ALS. Certain clinical features previously considered unlikely to occur in ALS are found on careful examination. Epidemiologic surveillance and recent studies of neurotoxic plant seeds used in Guam have shed light on the pathogenesis of endemic ALS. Extensive analyses of biochemical, metabolic, immunologic, viral, and toxic factors have provided provocative results requiring further studies. Reflecting on some of these hypotheses, therapeutic trials have been performed more vigorously than ever. Amyotrophic lateral sclerosis is now investigated at the molecular genetic level. Human autopsy and experimental animal studies have expanded our understanding of basic mechanisms involving motoneuronal degeneration. In the future, we must continue a relentless search for the pathogenesis of ALS, prospective clinical studies to define the limits of ALS, and well-designed, controlled therapeutic trials.

Amyotrophic Lateral Sclerosis↗